From the perspective of surface modification of biomaterials, graphene is very promising because of its unique physical and chemical properties. Herein, we report direct in situ fabrication of graphene on nitinol (NiTi) shape memory alloy by chemical vapor deposition (CVD) and investigate both the growth mechanism as well as surface bioactivity of the modified alloy. Growth of the graphene layer is independent of Ni but is rather correlated with the formation of the TiC phase on the surface. Graphene nucleates and grows on this carbide layer during exposure to CH4. The graphene layer is observed to promote the osteogenesis differentiation of mesenchymal stem cells and surface bioactivity. The use of graphene as a bioactive layer is a viable approach to improving the surface properties of NiTi-based dental and orthopedic implants and components.
Keywords: bioactivity; graphene; nitinol; stem cells; surface and interface.